Form Returns Null Values or Empty Values For Variables After Clicking OK Button

Question

I'm trying to create a new user based on a template user. Right now I just want to get the variables right, I just want to be able to select a template user, fill in the information that will be different, and click Create User. 
I'm not sure why this isn't working. I think the problem is in the code for the OK button or Enter keypress but I'm not sure what's wrong with the code I've entered. Any advice would be helpful. I'm sure it's something simple but I'm fairly new to powershell
and syntax has been rather tricky for me. Sorry if it's a rookie mistake and thanks for any advice.
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Drawing")
Write-Host "Creating The Form For Selecting Templates"
$TemplateForm = New-Object System.Windows.Forms.Form
$TemplateForm.Text = "Select a Template"
$TemplateForm.Size = New-Object System.Drawing.Size(640,700)
$TemplateForm.StartPosition = "CenterScreen"
Write-Host "Enabling Keystroke Response on Form"
$TemplateForm.KeyPreview = $True
Write-Host "Defining Keystroke Response for Enter Key"
$TemplateForm.Add_KeyDown({if ($_.KeyCode -eq "Enter")
{$SelectedTemplate=$TemplateListBox.SelectedItem;$newuserfirstname=$FnameTextBox.Text;$newuserlastname=$LnameTextBox.Text;$newusertitle=$TitleTextBox.Text;$newuserhiringmanager=$MgrNameTextBox.Text;$newuserphonenumber=$PhoneNumberTextBox.Text;$newuserdepartment=$DeptTextBox.Text;$TemplateForm.Close()}})
Write-Host "Defining Keystroke Response for Esc Key"
$TemplateForm.Add_KeyDown({if ($_.KeyCode -eq "Escape")
{$TemplateForm.Close()}})
Write-Host "Placing OK Button On Form"
$OKButton = New-Object System.Windows.Forms.Button
$OKButton.Location = New-Object System.Drawing.Size(75,550)
$OKButton.Size = New-Object System.Drawing.Size(75,23)
$OKButton.Text = "Create User"
$OKButton.Add_Click({$SelectedTemplate=$TemplateListBox.SelectedItem;$newuserfirstname=$FnameTextBox.Text;$newuserlastname=$LnameTextBox.Text;$newusertitle=$TitleTextBox.Text;$newuserhiringmanager=$MgrNameTextBox.Text;$newuserphonenumber=$PhoneNumberTextBox.Text;$newuserdepartment=$DeptTextBox.Text;$TemplateForm.Close()})
$TemplateForm.Controls.Add($OKButton)
Write-Host "Placing Cancel Button On Form"
$CancelButton = New-Object System.Windows.Forms.Button
$CancelButton.Location = New-Object System.Drawing.Size(150,550)
$CancelButton.Size = New-Object System.Drawing.Size(75,23)
$CancelButton.Text = "Cancel"
$CancelButton.Add_Click({$TemplateForm.Close()})
$TemplateForm.Controls.Add($CancelButton)
Write-Host "Placing Label On Template List Box"
$TemplateListLabel = New-Object System.Windows.Forms.Label
$TemplateListLabel.Location = New-Object System.Drawing.Size(10,20)
$TemplateListLabel.Size = New-Object System.Drawing.Size(280,20)
$TemplateListLabel.Text = "Please fill out the following new user information:"
$TemplateForm.Controls.Add($TemplateListLabel)
Write-Host "Creating Template List Box for Form"
$TemplateListBox = New-Object System.Windows.Forms.ListBox
$TemplateListBox.Location = New-Object System.Drawing.Size(10,40)
$TemplateListBox.Size = New-Object System.Drawing.Size(260,20)
$TemplateListBox.Height = 520
Write-Host "Placing Label On First Name Box for Form"
$FnameTextLabel = New-Object System.Windows.Forms.Label
$FnameTextLabel.Location = New-Object System.Drawing.Size(300,20)
$FnameTextLabel.Size = New-Object System.Drawing.Size(95,20)
$FnameTextLabel.Text = "First Name:"
$TemplateForm.Controls.Add($FnameTextLabel)
Write-Host "Creating First Name Box for Form"
$FnameTextBox = New-Object System.Windows.Forms.TextBox
$FnameTextBox.Location = New-Object System.Drawing.Size(300,40)
$FnameTextBox.Size = New-Object System.Drawing.Size(95,20)
$TemplateForm.Controls.Add($FnameTextBox)
Write-Host "Placing Label On Last Name Box for Form"
$LnameTextLabel = New-Object System.Windows.Forms.Label
$LnameTextLabel.Location = New-Object System.Drawing.Size(400,20)
$LnameTextLabel.Size = New-Object System.Drawing.Size(95,20)
$LnameTextLabel.Text = "Last Name:"
$TemplateForm.Controls.Add($LnameTextLabel)
Write-Host "Creating Last Name Box for Form"
$LnameTextBox = New-Object System.Windows.Forms.TextBox
$LnameTextBox.Location = New-Object System.Drawing.Size(400,40)
$LnameTextBox.Size = New-Object System.Drawing.Size(95,20)
$TemplateForm.Controls.Add($LnameTextBox)
Write-Host "Placing Label On Department Box for Form"
$DeptTextLabel = New-Object System.Windows.Forms.Label
$DeptTextLabel.Location = New-Object System.Drawing.Size(500,20)
$DeptTextLabel.Size = New-Object System.Drawing.Size(95,20)
$DeptTextLabel.Text = "Department:"
$TemplateForm.Controls.Add($DeptTextLabel)
Write-Host "Creating Department Box for Form"
$DeptTextBox = New-Object System.Windows.Forms.TextBox
$DeptTextBox.Location = New-Object System.Drawing.Size(500,40)
$DeptTextBox.Size = New-Object System.Drawing.Size(95,20)
$TemplateForm.Controls.Add($DeptTextBox)
Write-Host "Placing Label On Title Box for Form"
$TitleTextLabel = New-Object System.Windows.Forms.Label
$TitleTextLabel.Location = New-Object System.Drawing.Size(300,70)
$TitleTextLabel.Size = New-Object System.Drawing.Size(95,20)
$TitleTextLabel.Text = "Title:"
$TemplateForm.Controls.Add($TitleTextLabel)
Write-Host "Creating Title Box for Form"
$TitleTextBox = New-Object System.Windows.Forms.TextBox
$TitleTextBox.Location = New-Object System.Drawing.Size(300,90)
$TitleTextBox.Size = New-Object System.Drawing.Size(95,20)
$TemplateForm.Controls.Add($TitleTextBox)
Write-Host "Placing Label On Manager Name Box for Form"
$MgrNameTextLabel = New-Object System.Windows.Forms.Label
$MgrNameTextLabel.Location = New-Object System.Drawing.Size(400,70)
$MgrNameTextLabel.Size = New-Object System.Drawing.Size(95,20)
$MgrNameTextLabel.Text = "Manager's Name:"
$TemplateForm.Controls.Add($MgrNameTextLabel)
Write-Host "Creating Manager's Name Box for Form"
$MgrNameTextBox = New-Object System.Windows.Forms.TextBox
$MgrNameTextBox.Location = New-Object System.Drawing.Size(400,90)
$MgrNameTextBox.Size = New-Object System.Drawing.Size(95,20)
$TemplateForm.Controls.Add($MgrNameTextBox)
Write-Host "Placing Label On Manager Name Box for Form"
$PhoneNumberTextLabel = New-Object System.Windows.Forms.Label
$PhoneNumberTextLabel.Location = New-Object System.Drawing.Size(500,70)
$PhoneNumberTextLabel.Size = New-Object System.Drawing.Size(95,20)
$PhoneNumberTextLabel.Text = "Phone Number:"
$TemplateForm.Controls.Add($PhoneNumberTextLabel)
Write-Host "Creating Phone Number Box for Form"
$PhoneNumberTextBox = New-Object System.Windows.Forms.TextBox
$PhoneNumberTextBox.Location = New-Object System.Drawing.Size(500,90)
$PhoneNumberTextBox.Size = New-Object System.Drawing.Size(95,20)
$TemplateForm.Controls.Add($PhoneNumberTextBox)
Write-Host "Creating Fake List of Templates"
$TemplateGroupList = "Test"
$TemplateForm.Controls.Add($TemplateListBox)
Write-Host "Ensuring List Box appears in front of other windows"
$TemplateForm.Topmost = $True
$TemplateForm.Add_Shown({$TemplateForm.Activate()})
[void] $TemplateForm.ShowDialog()
$SelectedTemplate
$newuserfirstname
$newuserlastname
$newusertitle
$newuserhiringmanager
$newuserphonenumber
$newuserdepartment
Pause

Answer 1

If you plan on performing all of the work under the Click event, then you won't need to worry about assigning a Script scope to the variables, but if you are planning on using those variables outside of the Event, then David's answer is the way to go.
Another option is to use a hash table as it also works around the issue with variable scope in a UI Event.
#Define at beginning of script
$hashtable = @{}
$OKButton.Add_Click({$hashtable.SelectedTemplate=$Something})
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